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Move the float hash function into its own header.

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[SVN r32594]
This commit is contained in:
Daniel James
2006-02-05 19:51:29 +00:00
parent b922722090
commit 81483cc533
3 changed files with 57 additions and 33 deletions
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2
include/boost/functional/detail/float_functions.hpp
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@@ -6,6 +6,8 @@
#if !defined(BOOST_FUNCTIONAL_DETAIL_FLOAT_FUNCTIONS_HPP)
#define BOOST_FUNCTIONAL_DETAIL_FLOAT_FUNCTIONS_HPP
#include <cmath>
#if defined(_MSC_VER) && (_MSC_VER >= 1020)
# pragma once
#endif

54
include/boost/functional/detail/hash_float.hpp Normal file
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@@ -0,0 +1,54 @@
// (C) Copyright Daniel James 2005.
// Use, modification and distribution are subject to the
// Boost Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// Based on Peter Dimov's proposal
// http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2005/n1756.pdf
// issue 6.18.
#if !defined(BOOST_FUNCTIONAL_DETAIL_HASH_FLOAT_HEADER)
#define BOOST_FUNCTIONAL_DETAIL_HASH_FLOAT_HEADER
#if defined(_MSC_VER) && (_MSC_VER >= 1020)
# pragma once
#endif
#include <boost/functional/detail/float_functions.hpp>
namespace boost
{
namespace hash_detail
{
template <class T>
inline std::size_t float_hash_value(T v)
{
int exp = 0;
errno = 0;
v = boost::hash_detail::call_frexp(v, &exp);
if(errno) return 0;
std::size_t seed = 0;
std::size_t const length
= (std::numeric_limits<T>::digits +
std::numeric_limits<int>::digits - 1)
/ std::numeric_limits<int>::digits;
for(std::size_t i = 0; i < length; ++i)
{
v = boost::hash_detail::call_ldexp(v, std::numeric_limits<int>::digits);
int const part = static_cast<int>(v);
v -= part;
boost::hash_combine(seed, part);
}
boost::hash_combine(seed, exp);
return seed;
}
}
}
#endif

34
include/boost/functional/hash/hash.hpp
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@@ -16,11 +16,10 @@
#endif
#include <boost/functional/hash_fwd.hpp>
#include <cmath>
#include <functional>
#include <errno.h>
#include <boost/limits.hpp>
#include <boost/functional/detail/float_functions.hpp>
#include <boost/functional/detail/hash_float.hpp>
#include <boost/functional/detail/container_fwd.hpp>
#if defined(BOOST_NO_FUNCTION_TEMPLATE_ORDERING)
@@ -244,37 +243,6 @@ namespace boost
return hash_range(v.begin(), v.end());
}
namespace hash_detail
{
template <class T>
inline std::size_t float_hash_value(T v)
{
int exp = 0;
errno = 0;
v = boost::hash_detail::call_frexp(v, &exp);
if(errno) return 0;
std::size_t seed = 0;
std::size_t const length
= (std::numeric_limits<T>::digits +
std::numeric_limits<int>::digits - 1)
/ std::numeric_limits<int>::digits;
for(std::size_t i = 0; i < length; ++i)
{
v = boost::hash_detail::call_ldexp(v, std::numeric_limits<int>::digits);
int const part = static_cast<int>(v);
v -= part;
boost::hash_combine(seed, part);
}
boost::hash_combine(seed, exp);
return seed;
}
}
inline std::size_t hash_value(float v)
{
return boost::hash_detail::float_hash_value(v);